Guidelines for Permitting, Construction, and Monitoring of Retention Bulkheads in Underground Coal Mines; Information circular/2008

摘要

Many mining operations rely on retention bulkheads to provide a barrier between impounded water and active mine workings. However, bulkhead failures can cause catastrophic flooding that puts the underground workforce at risk. Underground observations and evaluations of existing bulkheads indicate that a systems approach is required when building an underground water or slurry retention system. In addition to engineering the bulkhead, the designer must ensure the quality control of materials and workmanship of the bulkhead, the reaction of the mine strata when exposed to water under pressure, and methods to monitor the performance of the retention system. Researchers from the National Institute for Occupational Safety and Health (NIOSH), with the assistance of the Mine Safety and Health Administration (MSHA), conducted an extensive review of bulkhead permits submitted to the MSHA Technical Support office in Bruceton, PA. In addition, the researchers visited accessible bulkhead installations at underground mining operations to gather information related to construction practices, maintenance issues, and monitoring and emergency response procedures. Several key items were identified that must be considered when permitting the installation of an underground fluid retention system. (1) In general, bulkheads are installed across mine openings to create an area for an underground impoundment. (2) The underground impoundment should be located at an elevation that will still permit personnel to evacuate to the surface if a breach occurs. (3) The bulkhead design must consider all sources of fluid that could increase the pressure on the structure and design for the maximum anticipated fluid level. (4) Strata supporting the bulkheads must be tested and deemed competent to remain stable for the life of the impoundment. floor material that is affected by water, damaged, or fractured by mining must (5) A detailed construction plan that covers each phase of the construction process from site preparation through completion of the installation must be developed. (6) Routine monitoring the performance of the underground fluid retention system is essential and will be required for the life of the impoundment.